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Shawn Kenny, Ph.D., P.Eng. Assistant Professor Faculty of Engineering and Applied Science Memorial University of Newfoundland ENGI.

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Presentation on theme: "Shawn Kenny, Ph.D., P.Eng. Assistant Professor Faculty of Engineering and Applied Science Memorial University of Newfoundland ENGI."— Presentation transcript:

1 Shawn Kenny, Ph.D., P.Eng. Assistant Professor Faculty of Engineering and Applied Science Memorial University of Newfoundland ENGI 1313 Mechanics I Lecture 31:Mid-Term Review

2 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 2 Overall Mid-Term Results Class Statistics (259) Average 67% Standard deviation 17% Standard deviation between sections 3% Solution Posted

3 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 3 Term A/B Exam (Mon. Oct 22) Results are not Back Student Numbers

4 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 4 No Record of Mid-Term Exam Contact Me Immediately to Resolve Student Numbers

5 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 5 Problem 1 Determine the components of the F force acting along the u and v axes. Given: 1 = 70 2 = 45 3 = 60 F = 250N

6 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 6 Problem 1 (cont.) Problem Characteristics Force vectors No right rectangular coordinate system Forces on specified axes Solution Method Parallelogram or triangle construction Law of sines

7 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 7 Problem 1 (cont.) Force Triangle F = 250 N FvFv FuFu 2 = 45 1 = 70

8 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 8 Problem 2 The three cables are used to support the lamp of weight W. Determine the force developed in each cable for equilibrium. Given: a = 4 m b = 4 m c = 2 m W = 600 N 4 m 2 m 4 m W = 600 N

9 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 9 Problem 2 (cont.) Problem Characteristics Particle Equilibrium Scalar or vector approach Solution Method Summation of Forces 4 m 2 m 4 m W = 600 N

10 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 10 Problem 2 (cont.) FBD and Unit Vectors F AD F AC F AB 4 m 2 m 4 m W = 600 N

11 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 11 Problem 2 (cont.) Equilibrium Equation Three Equations F AD F AC F AB 4 m 2 m 4 m W = 600 N

12 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 12 Problem 3 Force F is applied to the handle of the wrench. Determine the angle between the tail of the force F and the handle AB. Given: a = 0.30 m b = 0.50 m F = 80 N 1 = 30 2 = m F = 80N 0.3 m 1 2

13 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 13 Problem 3 (cont.) Problem Characteristics Vector projection Solution Method Dot product 0.5 m F = 80N 0.3 m 1 2

14 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 14 Problem 3 (cont.) Unit Vectors Dot Product 0.5 m F = 80N 0.3 m 30 45

15 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 15 Problem 4 The hood of the automobile is supported by the strut AB, which exerts a force F on the hood. Determine the moment of this force about the hinged axis y. Given: a = 0.60 m b = 1.50 m c = 0.25 m d = 1.00 m F = 100 N

16 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 16 Problem 4 (cont.) Problem Characteristics Moment about a specified axis Solution Method Triple scalar product

17 ENGI 1313 Statics I – Lecture 31© 2007 S. Kenny, Ph.D., P.Eng. 17 Problem 4 (cont.) Unit Vector Moment about Y-axis


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